1. Field of the Invention
The present invention relates to a vehicle mirror apparatus having a structure that seals a gap between a shaft portion of a mover and a hole in a sensor case in a mirror surface angle detection device for the vehicle mirror apparatus, the mirror surface angle detection device having a structure in which a mover for mirror surface angle detection projects from the hole in the sensor case in such a manner that the mover is movable in an axial direction thereof. The seal structure of the present invention eliminates the need for an O ring cover, which is needed in a conventional structure.
2. Description of the Related Art
In vehicle mirror apparatuses including a tilting device (mirror surface angle adjustment actuator), a mirror surface angle detection device is installed in, e.g., what is called a memory mirror or what is called a reverse interlock mirror. A memory mirror is a mirror that automatically adjusts a mirror surface angle to a prestored angle. A reverse interlock mirror is a mirror that in association with gear shift operation means of the vehicle being thrown into a reverse position, automatically rotates a mirror surface of a vehicle outside mirror downward by a predetermined amount of angle to enable a driver to view an area around the rear wheel. As a conventional mirror surface angle detection device for a vehicle mirror apparatus, there is one described in Japanese Patent Laid-Open No. 2001-294091. FIG. 12 illustrates the mirror surface angle detection device described in Japanese Patent Laid-Open No. 2001-294091. In a mirror surface angle detection device 200, rod-like movers 204 and 206 are biased by respective springs 208 and 210 and housed in a case body 202 of a sensor case 201 in such a manner that the movers 204 and 206 are movable in respective axial directions. Shaft portions of the movers 204 and 206 project to the outside of the sensor case 201 from respective holes 212 and 214 in the case body 202 in such a manner that the shaft portions are movable in the respective axial directions. Contact members 216 and 218 are attached to respective rear end portions of the movers 204 and 206. A print wiring board 224 with resistors 220 and 222 printed on a surface thereof is housed in the case body 202. The contact members 216 and 218 are in contact with the resistors 220 and 222, respectively, and along with movement of the movers 204 and 206, slide respective surfaces of the resistors 220 and 222. A lower opening 202a of the case body 202 is occluded by attaching a case cover 226 to the case body 202 via screws 227. The case body 202 and the case cover 226 provide the sensor case 201. Balls 205 and 207 are attached to respective tips of the movers 204 and 206 biased by the springs 208 and 210. The balls 205 and 207 press and abut against respective positions in a back side of a mirror (not illustrated), the positions being off a tilting center. Upon the mirror being tilted vertically and horizontally with the tilting center as a center as a result of being driven by respective motors (not illustrated), the movers 204 and 206 move following the mirror in the respective axial directions. Along with the movement of the movers 204 and 206, positions where the contact member 216 and 218 are in contact with the respective resistors 220 and 222 change, and thus, the contact positions are detected as voltage values through a connector 228, whereby respective mirror surface angles in the vertical and horizontal directions are detected. Structures that seals gaps between the shaft portions of the movers 204 and 206 and the holes 212 and 214 in the case body 202 are configured as follows. At an upper surface of the case body 202, circular walls 230 and 232 are formed so as to surround the holes 212 and 214. In respective spaces inside the walls 230 and 232, respective O rings 234 and 236 are arranged, and O ring covers 238 and 240 are further fitted in the respective spaces. Vertical holes 238b and 240b are formed in the respective O ring covers 238 and 240. On the case body 202, projections 239 are formed at respective positions corresponding to the holes 238b and 240b. The projections 239 are put in the respective holes 238b and 240b and respective upper ends of the projections 239 that project above the holes 238b and 240b are crushed by thermal caulking, whereby the O ring covers 238 and 240 are fixedly attached to the case body 202. Here, the O rings 234 and 236 are held between the upper surface of the case body 202 and respective lower surfaces of the O ring covers 238 and 240. The shaft portions of the movers 204 and 206 project to the outside of the mirror surface angle detection device 200 through the center holes 234a and 236a in the O rings 234 and 236 and the center holes 238a and 240a in the O ring covers 238 and 240, respectively. Gaps between the shaft portions of the movers 204 and 206 and the holes 212 and 214 in the case body 202 are sealed by the O rings 234 and 236, respectively, and thus, intrusion of water into the sensor case 201 through the gaps is blocked. When the movers 204 and 206 are moved in the respective axial directions, outer peripheral surfaces of the shaft portions of the movers 204 and 206 slide on respective inner peripheral surfaces of the center holes 234a and 236a in the O rings 234 and 236.
A tilting device for a vehicle mirror apparatus equipped with a mirror surface angle detection device having a structure similar to that in FIG. 12 has been put into practical use. FIGS. 13A and 13B are schematic diagrams of the tilting device. In a tilting device 242, a tilting member 246 is supported on a housing 244 (base member) so as to be tiltable in vertical and horizontal directions. A mirror holder (not illustrated) that holds a mirror is attached to a front surface of the tilting member 246. By means of driving motors housed in an actuator housing 244 and drive devices that each include a transmission mechanism, the tilting member 246 vertically and horizontally tilts relative to the actuator housing 244. A mirror surface angle detection device 200′ having a structure similar to that in FIG. 12 is attached to a back surface of the actuator housing 244 by means of engagement using lugs (not illustrated). Movers in the mirror surface angle detection device 200′ (corresponding to the movers 204 and 206 in FIG. 12) penetrate the actuator housing 244 and balls attached to respective tips of the movers (corresponding to balls 205 and 207 in FIG. 12) press and abut against a back surface of the tilting member 246. FIG. 14 illustrates a seal structure in the mirror surface angle detection device 200′ in FIG. 13. Parts that are in common with the mirror surface angle detection device 200 in FIG. 12 are provided with reference numerals that are the same as those of the mirror surface angle detection device 200. At a surface of the actuator housing 244 that faces a case body 202, a circular wall 230′ is formed so as to surround a hole 212. An O ring 234 is arranged in a space inside the wall 230′, and an O ring cover 238′ is further put on the O ring 234. Vertical holes 238b are formed in the O ring cover 238′. Projections 239 are formed at respective positions in the case body 202 corresponding to the respective holes 238b. The projections 239 are put into the holes 238b. Extremity portions 239a of the projections 239 that project from the holes 238b are crushed by means of thermal caulking, whereby the O ring cover 238′ is fixedly attached to the case body 202. Here, the O ring 234 is held between surfaces of the case body 202 and the O ring cover 238′ that face each other. A shaft portion of a mover 204 projects to the outside of the mirror surface angle detection device 200′ through a center hole 234a of the O ring 234 and a center hole 238a of the O ring cover 238′. The shaft portion further penetrates the actuator housing 244 through a hole 244a in the actuator housing 244, and a ball attached to a tip of the shaft portion against (corresponding to the ball 205 in FIG. 12) presses and abuts the back surface of the tilting member 246 (FIG. 13). A gap G between the shaft portion of the mover 204 and the hole 212 in the case body 202 is sealed by the O ring 234, and thus, intrusion of water into a sensor case 201 through the gap G is blocked. When the mover 204 moves in an axial direction thereof, an outer peripheral surface of the shaft portion of the mover 204 slides on an inner peripheral surface of the center hole 234a of the O ring 234.
The seal structure in FIG. 14 requires the O ring cover 238′, resulting in the problem of an increase in the number of components by that amount. Also, a process of assembling the mirror surface angle detection device 200′ requires a step of fixing the O ring cover 238′ to the case body 202 by means of thermal caulking. Furthermore, there is the problem of an increase in the entire thickness of the combination of the tilting device 242 and the mirror surface angle detection device 200′ by the thickness of the O ring cover 238′.
The present invention is intended to solve the aforementioned problems of the conventional techniques, and is intended to provide a vehicle mirror apparatus having a seal structure that eliminates the need for an O ring cover.